107 results about "Discrete element model" patented technology

One embodiment of the invention provides a computer-implemented method for discrete element modelling of a plurality of discrete elements corresponding to particles and physical geometry elements. The modelling performs a simulation through time of physical interactions of the particles with each other and with the physical geometry elements in a three-dimensional space. The method comprises providing a virtual geometry object comprising a user-defined shape. The virtual geometry object does not undergo physical interaction with the particles or physical geometry elements during the simulation. The method further comprises receiving user-defined parameters for determining the position, orientation and any movement of the virtual geometry object with respect to the three-dimensional space. The method further comprises locating the virtual geometry object in the three-dimensional space during the simulation in accordance with the user-defined parameters and identifying the particles, physical geometry elements and/or physical interactions having a particular relationship with respect to the virtual geometry object. The identified elements can then be analysed by the user, for example to determine the number of particles located at a given time within a specific region of the simulation space (as defined by the virtual geometry object).

A mesh generation tool that is programmatically integrated with a system-level design and simulation environment, thereby enabling the direct generation of PDE solver input from a system-level design and simulation environment and a method for using the mesh generation tool are disclosed. Automatic mesh generation and optimization is improved by making available additional information about the nature and purpose of certain design components to the mesh generation tool. Specifically, the parameters of the components in the device schematic, which represent a user-defined decomposition of a larger MEMS design into smaller entities of clear physical purpose, are made available to the mesh generation tool. The link established between the system-level design and PDE analyses allows the user to move between the two levels of abstraction. The mesh generation tool retrieves information from the components and connectors of a schematic of a MEMS device, and produces a discrete element model suitable for numerical PDE analysis by the finite element (FEM) and boundary element (BEM) methods. A direct link from a schematic model to a mesh model helps the user to produce an optimal mesh for PDE analysis, thereby avoiding considerable unnecessary computation.

The invention discloses a visual uniaxial penetrating test-based bituminous mixture homogeneity evaluation method, which comprises the following steps: carrying out indoor molding or drilling a cylindrical core sample on site, acquiring two-dimensional horizontal section images of a plurality of bituminous mixture test pieces through tomoscan of an industrial CT machine, and then preprocessing and intensifying the two-dimensional horizontal section images acquired by the CT machine to generate gray images; recognizing and segmenting the processed bituminous mixture section gray images to obtain a boundary coordinate of each aggregate and gap in the bituminous mixture section images, establishing a three-dimensional discrete element model of the bituminous mixture and carrying out a virtual uniaxial penetration test, and evaluating the bituminous mixture homogeneity by using the uniaxial penetration strength index variable coefficient obtained by the test. The bituminous mixture homogeneity evaluation method is based on the visual uniaxial penetrating test, and the bituminous mixture homogeneity is quantitatively evaluated by using the uniaxial penetration strength index variable coefficient, so the industrial practicability and maneuverability are very strong.

The invention discloses a grading optimization method for an asphalt mixture under virtual state. The method includes the steps of: on the basis of grading that needs to optimize according to practical demand, in three-dimensional discrete element software PFC3D, randomly generating an asphalt mixture mechanical test three-dimensional discrete element model (including uniaxial penetration test, low temperature split test, uniaxial compression test and shear fatigue test) which satisfies a target grading, wherein the generation process of the three-dimensional discrete element model, which satisfies the target grading, is the base of asphalt mixture grading optimization; and comparing mechanical performance evaluation results of various grading to obtain a grading having best mechanical performance. The method has strong operability, convenience and representativeness.

The invention discloses a universal simulation box used for three-dimensional discrete element modeling and simulation of a rock and soil mass. 1) a universal simulation box is established, specified-size boundary plates in six directions of a box body are generated, the boundary plates are composed of a series of sphere particles, smaller-size buffer boundary pressure plates are respectively generated inside the six boundary plates, and the three-dimensional simulation box is established; 2) a particle accumulation body is generated in the box body, and no-gravity particles are randomly generated in the box body; 3) a three-dimensional model of different structures is established, files including delamination and demarcation coordinate files are imported, the particles outside an outlineare removed, and the three-dimensional model of the structures is formed; 4) material properties of the rock and soil mass are assigned to the three-dimensional model, a material attribute file of therock and soil mass is imported, parameters of the rock and soil mass are converted into parameters of the particles according to conversion formulas, the parameters are assigned to the particles, anda three-dimensional discrete element model with specified elastic properties and failure properties is established; and 5) loading of force, displacement and vibration is carried out through the boundary pressure plates, displacement and vibration are applied through boundaries, loads such as stress action are applied through the pressure plates, iteration operating is carried out, and a result is output.

The invention discloses a construction method for a two-dimensional discrete element model of a mother rock and a particle material thereof. The construction method comprises three steps of grading curve correction, mother rock test discrete element modeling and particle material discrete element modeling. The step of grading curve correction comprises the sub-step of redistributing the mass of a smallest particle fraction to the remaining particle fractions according to the quality ratio of particles of particle fractions except the particle fraction of a finest stage in a grading curve to obtain a correction simulation curve in a computer operation simulation range and a particle diameter range of basic particle units. The particle material discrete element modeling comprises the sub-step of: firstly, randomly generating a rock area outline; secondly, forming a rock unit from the basic particle units; thirdly, assigning contact attributes in rocks; finally, assigning the contact attributes between the rocks. In rock aggregation generated according to the construction method, good randomness and diversity are available for the particle number and the form of composed rocks and the actual outline of the rocks; the rock size is generated according to a certain grading condition and satisfies the requirement of certain porosities.

The invention discloses a temperature field analysis method of a bituminous mixture test piece on the basis of discrete element simulation, belongs to the technical field of bituminous mixture, and solves the problem that a finite element method can not accurately analyze the internal temperature field of the bituminous mixture test piece in a high-temperature environment. The temperature field analysis method comprises the following steps: firstly, forming the bituminous mixture test piece, collecting a digital image of irregular aggregate distribution, and converting the digital image into a digital test piece of a two-dimensional CAD (Computer-Aided Design) image format after the digital image is subjected to image processing; then, importing discrete element software, independently generating irregular aggregate and bituminous mortar according to the positions of aggregate blocks and the bituminous mortar, and constructing a two-dimensional test piece discrete element model; simulating a situation that the test piece is heated in the high-temperature environment, setting a boundary condition of the test piece model, the thermophysical property parameters of the aggregate and the bituminous mortar and the internal contact thermal resistance of a unit; and applying certain constant-high-temperature and room-temperature heat flow around the test piece model, recording the temperature change situations of each point in the test piece at different moments, drawing a comparison graph, and combining with a temperature field and a heat flow distribution cloud chart generated by the software to analyze the temperature field of the bituminous mixture test piece.

The invention discloses a discrete element method based method for improving the particle discrete contact detection efficiency and belongs to the technical field of particle discrete element model construction. The discrete element method based method for improving the particle discrete contact detection efficiency is achieved by solving the number of contactable particles of one particle at a moment. Used mathematic models in the discrete element method based method are simple geometric models, the relationship between the number of contactable particles and the semi-diameter of the central particle and contact particles is obtained due to calculation of the geometric models, calculation times are reduced due to the fact that relational expressions are added to a program, then the program for simulating the calculation is out of the loop, the calculation times are reduced, and the efficiency is improved. Compared with the existing models, the calculation amount in the discrete element method based method is effectively reduced and simulation calculation of numerical values in large scale can be performed through common devices.

The invention discloses a building method of a discrete element module of true aggregate particles based on an X-ray CT image which is provided to the aggregate particles in a bituminous mixture test piece of numerical analysis of a bituminous mixture, so as to realize that the discrete element module of true aggregate particles with highly fitted geometrical shape of a true aggregation and the minimal quantity of discrete elements can be automatically built. According to the building method provided by the invention, based on the discrete element analysis of the bituminous mixture test piece in a microstructure, the automatic switching between the X-ray CT section image of the bituminous mixture test piece and the discrete element module of true aggregate particles with precisely fitted geometrical shape of the true aggregation and the minimal quantity of discrete elements can be completed to assist the building of the discrete element module of the bituminous mixture test piece.

The invention is suitable for the technical field of unloading elephant trunks, and provides a space transhipment unloading elephant trunk design method based on a discrete element method, wherein a space transhipment unloading elephant trunk is composed of discrete elements of each segment. The design method comprises the following steps of: building a three-dimensional model of the discrete element of each segment through a three-dimensional software, and importing the three-dimensional model in a discrete element model software EDEM; creating a particle model of the material to be conveyed by the unloading elephant trunk, and importing the particle model of the material in the EDEM; determining simulation parameters, wherein the simulation parameters include operating speed and particle conveying quantity of a superior unloading device and a lower receiving device, and also include own material attributes of the particle and the discrete element, and contact attribute between the two; finishing simulation, and outputting simulation result. According to the invention, the discrete element method is introduced in the design process of the space transhipment unloading elephant trunk, movement locus of material flow in the elephant trunk can be fitted accurately, and variation of stress on each part of the elephant trunk can be calculated.

An end compaction point of a clastic sediment within a subsurface region is predicted by establishing a first grain size distribution, wherein the first grain size distribution is a measured grain size distribution, or a predicted grain size distribution. A discrete element model of the subsurface region is initialized, wherein the model comprises a model volume including a base, periodic horizontal boundaries, and soft objects representative of particles of the first grain distribution at a predetermined porosity. A final packing state of the clastic sediment is predicted by iteratively running the model, wherein the final packing state of the clastic sediment is based on packing of the soft objects with a pack and based on the first grain size distribution, wherein soft objects within the model are capable of overlapping with adjacent soft objects within the model.

The invention discloses a discrete element modeling method for a rock and earth mass triaxial test taking film effect. The method includes following steps: S1, modeling a sample preparing container; S2, modeling a rock-earth mass sample; S3, endowing the generated rock-earth mass sample with material attribute of given sample units, balancing stress among the sample units to complete making of the rock-earth mass sample; S4, building an elastic film, replacing a rigid barrel of a sample preparing container model with the elastic film, setting corresponding material attribute for the elastic film to complete building of a triaxial test discrete element model. Further, the invention further discloses a numerical simulation method based on the discrete element model. According to given pressurizing conditions, stress loading is adopted to axially pressurize the rock-earth mass sample, and lateral confining pressure is applied on the rock-earth mass sample through water pressure. A film unit is adopted to simulate a latex film in the triaxial test, and flexible boundary of the latex film better conforms to actual circumstance of indoor triaxial test numerical simulation.

The invention provides a rapid simulation modeling method for multi-field coupled discrete elements of soil water loss and cracking which is a multi-field coupled discrete element modeling and simulation method used in cohesive soil water loss and cracking. The method comprises following steps: 1) constructing a three-dimensional close packing discrete element model, giving the water content attribute to the element, and using the finite difference theory to simulate a water field; 2) building coupling of the water field and a stress field taking account of influences on mechanical properties such as tensile strength of discrete elements from water field; 3) assuming that the surface water content of the soil three-dimensional close packing discrete element model evaporates at a certain speed, the relationship between the water content and the three-dimensional discrete element shrinkage of the soil is established based on the experimental data, and the deformation and fracture of the three-dimensional discrete element of the soil is calculated in the discrete element method to realize rapid simulation and modeling of multi-field coupled discrete element for evaporation water loss, shrinkage and cracking deformation of clay soil. Multi-filed coupled simulation of evaporation water loss, shrinkage and cracking deformation of clay soil is achieved. The invention provides a novel method for simulating soil deformation and fracture under multi-field effect.

the invention discloses a numerical simulation method for aging degradation of mechanical properties of carbonate rock under water action which includes such step as establishing a generalized model of mechanical property deterioration mechanism of carbonate rock under the action of water, setting up the generalized model of mechanical property deterioration mechanism of carbonate rock under the action of water, setting up the generalized model of mechanical property degradation mechanism of carbonate rock under the action of water. Step 22, establishing a discrete element model of aging deterioration of mechanical properties of carbonate rock under different immersion conditions according to the mechanism generalization model obtained in the step 1, and obtaining a quantitative correlation of mechanical properties with time of bonding between blocks of polygonal blocks under different immersion conditions; step 3, calibrating that mechanical parameters of the discrete element model; Carbonate rock mechanics tests under different immersion conditions and immersion time were carried out to calibrate the mechanical parameters of the discrete element model in step 2. Step 4, simulating the mechanical properties of carbonate rock under different immersion conditions by using the calibrated parameters of the discrete element model. The invention truly reflects the carbonate rock-water water interaction principle, a two-stage deterioration model and its discrete element simulation method are proposed.

The invention discloses a discrete element analysis method of slender type metal tube drug tamping state, and relates to the field of computer model analysis. The method comprises the following steps: 1) establishing a slender type metal tube model; 2) establishing a drug particle feeding model; 3) establishing a drug particle model; 4) simulating of the tamping action of the slender type metal tube; 5) observing the movement, of the drug particles in the slender type metal tube and the drug particle density change process in the tamping action in simulation mode by using the established discrete element model.

The invention provides a grinding wheel discrete element modeling method with consideration of the abrasive particle shape and distribution randomness. The grinding wheel discrete element modeling method comprises the following main steps: (1) establishing a square calculation area and generating closely-arranged particles inside the square calculation area; (2) defining two big concentric circlesat the center of the square, defining the internal circle as the outline of an adhesive body, and defining the area between the internal circle and the external circle as an abrasive particle distribution area; (3) defining two small concentric circles which comprise random polygons; (4) grouping the particles, defining the particles in the polygons as an abrasive particle group, and defining theparticles in the internal circle of the big concentric circles as an adhesive body group; (5) removing the particles outside the abrasive particle group and the adhesive body group; and (6) selectinga suitable contact model and establishing a two-dimensional grinding wheel discrete element model. According to the grinding wheel discrete element modeling method provided by the invention, the sizes and shapes of abrasive particles on the surface of a grinding wheel as well as the randomness of mutual positions among the abrasive particles are sufficiently considered, so that the actual surfaceappearance of the grinding wheel can be represented more truly and vividly.

The invention relates to a block discrete element model generation method based on a progressive finite element mesh and a Voronoi segmentation method and belongs to the field of numerical calculation. The method includes the steps of S1, drawing modeling information by using CAD; S2, reading the modeling information and generating a high-quality, continuous and progressive triangular mesh; S3, generating a discrete model and outputting a final calculation file; S4, integrating steps S1-S3 into software, so that a DDA block discrete element model, a UDEC block discrete element model and a 3DECblock discrete element model which are directly used for calculation are generated directly by only drawing CAD drawings and defining the minimum size of blocks. A specific block size distribution rule or size data can be defined, the block discrete element models which satisfy specific spatial distribution are generated, and the problem that a given size distribution rule cannot be generated according to current methods is solved.

The invention discloses a semi-flexible pavement interface mesomechanics researching method under a vehicle load effect, and belongs to the technical field of pavement materials. The method solves theproblems of many modeling troubles, high calculation difficulty and low result accuracy in current semi-flexible pavement interface mesomechanics researches. The method based on a discrete element method comprises the steps that firstly, discrete element numerical simulation software is adopted to generate a two-dimensional discrete element model in the same grade as an actual semi-flexible pavement bituminous-mixture framework; then, existing functions in the software and a mechanical model are combined to define properties of each constituent material and the interface connection mode of each constituent material separately; finally, simulated vehicle load is added on the basis of the existing models, the mechanical response condition of a semi-flexible pavement interface is monitored during loading, shear force, pull force, pressure stress and displacement of the interface are recorded under the load effect, and the strained condition of the interface is evaluated. The semi-flexible pavement interface mesomechanics researching method has the advantages of being visible in expression, easy and accurate in calculation, wide in application range and applicable to mesomechanics researches of bituminous pavement interfaces.

The invention relates to a shot peening strengthening numerical simulation method considering coupling of a finite element and a discrete element of surface roughness, which comprises the following steps: (1) establishing an autocorrelation function based on Gaussian distribution to represent the real surface roughness of a part, and extracting data information of the surface roughness by using MATLAB mathematical software; (2) importing the data information of the surface roughness into PROE three-dimensional modeling software, carrying out surface smoothing treatment through fitting, and establishing a three-dimensional shell model for representing the surface roughness of the part; (3) importing the three-dimensional shell model into ABAQUS finite element software, and establishing a part finite element model considering the surface roughness on an ABAQUS/CAE platform; (4) by modifying the inp file of the ABAQUS, creating a particle generator, establishing a discrete element model of the shot flow in the shot peening strengthening process, and controlling related parameters of the shot flow according to actual shot peening working conditions; and (5) utilizing an ABAQUS/Expressexplicit dynamics algorithm to carry out shot peening numerical simulation calculation considering coupling of a finite element and a discrete element of the surface roughness in the shot peening process of the part.

The invention discloses a method for establishing a multi-scale model of medicament particles during a powder compaction process of a long thin metal pipe, and belongs to the field of computer simulation analysis. The method specifically comprises the following steps of (1) establishing a long thin metal pipe model; (2) establishing a medicament particle adding model; (3) establishing a medicament particle model; (4) establishing a long thin metal pipe compaction action model; (5) carrying out compaction simulation by utilizing discrete meta models which are established from the step (1) to the step (4). According to the method for establishing the multi-scale model of the medicament particles during the powder compaction process of the long thin metal pipe, disclosed by the invention, through establishing a multi-scale compaction model of the powder particle, the movement of the medicament particles at the inner part of the long thin metal pipe and a density changing process of the medicament particles in a compaction action are simulated by utilizing a computer, and a feasible theory basis is provided for a compaction technology of a compaction device based on impact vibration.

The invention provides a discrete element modeling method for stochastic void defect materials based on hyperelliptic equation, which can randomly generate ellipse, rhombus, star or rectangular cavitydefects with different flatness by controlling parameters, and is used for discrete element simulation research of hard and brittle materials. The concrete steps are as follows: defining the main physical parameters of the material, generating particles in a closed calculation area and assigning microscopic contact property parameters to the particles, and randomly determining a certain number ofvoid defect centers with random positions; Based on the hyperelliptic equation, the hole defect patterns with different shapes are constructed at each center point. Delete the particles in each holedefect pattern, select the appropriate contact model, delete the wall of the closed area, and form the discrete element model of the hole defect. The method of the invention is simple and feasible, and the size, shape, angle and flatness of the formed hole defects are controllable, so that the generated material model is closer to the reality, so that the simulation calculation result is more accurate, and the simulation effectiveness is improved.

The invention discloses a discrete element analysis method for propagation and damage of a coating crack in a cutting process of a coated cutting tool. The discrete element analysis method comprises the following analysis steps of 1) establishing the coated cutting tool and a discrete element model of chips; 2) selecting a suitable contact model and calibrating microscopic parameters of the discrete element model through a mechanical property test; 3) simulating the coated cutting tool and a cutting processing process; 4) observing and recording the conditions of propagation and damage of the coating crack of the coated cutting tool. The discrete element analysis method has the following technical effect that 1, long-distance movement between the coated cutting tool and the chips is simulated by utilizing a method of a periodic boundary; the continuous long chip models are simplified to a periodic flow model of a small section of chips in contact with the coated cutting tool; the number of the units of the chip model is greatly reduced, and the calculated amount and the computation time are greatly reduced; 2, visualization of propagation and damage of the coating crack of the coated cutting tool in a cutting processing process is implemented, through the model states of several time points captured for the cutting processing process of the coated cutting tool, the conditions of propagation and damage of the coating crack of the coated cutting tool in the processing process can be directly observed.

The invention discloses a steel bridge deck pavement interlayer shear test simulation method based on discrete-continuous coupling. The method comprises the following steps: firstly, carrying out themodeling in PFC3D software, and forming a three-dimensional discrete element model of a steel bridge deck pavement asphalt pavement layer; secondly, conducting the modeling in FLAC3D software, and forming a steel bridge deck slab three-dimensional continuous model; thirdly, realizing data exchange between the PFC3D model and the FLAC3D model by utilizing the Socket I/O function of the PFC3D software and the FLAC3D software; and finally, loading and shearing the model, changing the mesoscopic parameters of the three-dimensional discrete element model of the asphalt pavement layer and the material parameters of the steel bridge deck, and analyzing the influence factors of the interlayer shearing of the steel bridge deck pavement. According to the method, the advantages of a discrete elementmethod and a finite element method are integrated. The mesoscopic characteristics of asphalt concrete serving as a multi-phase composite material and the characteristics of a steel bridge deck linearelastic material are considered. The simulation result better conforms to engineering practice. The obtained data can be used for guiding the design of a composite structure of a steel bridge deck pavement system.

The invention provides a steel bridge deck pavement interlayer shear fatigue behavior simulation method based on discrete elements. The method comprises the following specific steps of firstly, generating the asphalt pavement layer discrete element models with the same sizes and grades according to an indoor test, then generating the steel bridge deck three-dimensional discrete element models, andcombining into a steel bridge deck pavement composite test piece model; secondly, endowing the corresponding mesomechanics parameters to the mutual contact and bonding among a generated coarse aggregate unit, an asphalt mortar unit and a steel bridge deck unit according to the macromechanics parameters; and finally, controlling a loading wall body to continuously adjust the speed by utilizing anFISH language in a PFC3D to realize different forms of periodic loads to carry out fatigue shearing, and real-timely collecting the fatigue loading frequency, the shearing deformation amount and the number and paths of the interlayer crack development in the simulation process, when the shearing deformation amount reaches a limit value, ending the simulation, exporting a data result, and analyzingthe mechanism of the steel bridge deck pavement interlayer shearing fatigue damage.